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gs 750 jetting

  • Thread starter Thread starter cjd73
  • Start date Start date
C

cjd73

Guest
Hello, I have a 77 gs750 with pods and 4-1 exhaust the carbs are completely stock:

97.5 Mains
27.5 Pilots

I have found the Keyster kit KS-0231 which has

102 Mains
15 pilots

Can I use this kit? Any suggestions are more than welcome.

Cheers,
Christopher.
 
NO...

Personal opinion, STAY AWAY from the Keyster kits! :confused:

Go with a DynoJet Stage #3 kit and be happy.

http://www.dynojet.com/jetkits/index.aspx


Welcome to the GSR...there are a few here that know from whence they speak.


BassCliff will be along shortly to throw out the faded Red Carpet! :D
 
Last edited:
Dave8338 said:
NO...

Personal opinion, STAY AWAY from the Keyster kits! :confused:

Go with a DynoJet Stage #3 kit and be happy.

http://www.dynojet.com/jetkits/index.aspx


Welcome to the GSR...there are a few here that know from whence they speak.


BassCliff will be along shortly to throw out the faded Red Carpet! :D
Click to expand...

There isn't a kit for the 750, the jets you have don't sound correct either. Stock mains should be 102.5 or maybe 100.
You probably need about a 115 or bigger.
Buy Mikuni main jets, raise the needle a tad, keep the same pilots.
Plug chops will tell you where to go.
 
Last edited:
Thanks Dave8338, I did get a reply from Michael at Dynojet and they do not have anything form my application, booo.

tkent02 - For my engine number these are correct, according to Haynes. Other engine numbers are 100 mains and 15 pilots. I wonder if this is due to the bike being Canadian and emission standards differences. So if my stock mains are 97.5 and pilots 27.5 does your advice still stand?

Cheers.
 
Try it and see, I have not tuned a Canadian spec 750 for pods and pipe.
It will probably be somewhere near the right ballpark.
 
cjd73 said:
Hello, I have a 77 gs750 with pods and 4-1 exhaust the carbs are completely stock:

97.5 Mains
27.5 Pilots

I have found the Keyster kit KS-0231 which has

102 Mains
15 pilots

Can I use this kit? Any suggestions are more than welcome.

Cheers,
Christopher.
Click to expand...


hey man dont get kits all you need is main jets and possibly pilot jets if your so inclined like i was! service manual tells stock jetting for our bikes is 100/15 i have 120/15 and my pods are emgo (not the foam) but they are still crappy as hell but its too lean for MY bike; in the high end rpm lots of popping occurs, maybe with k and n it would be fine with 120, i am going back to 125.... in your situation you cant go wrong with 120 and keeping the stock pilots
 
I, too, want to explore pods and jetting for my 78 GS750. I have air box (hate it) and VH 4-1 exhaust. Right now it is running lean but shows no air leaks. As I wrestle with the snipe hunt for this problem, I wonder if that is a pilot jet problem as well? In any event, I want to switch to pods and adjust the jetting.

My mains are 102.5. How do I check the pilot jet size? In any event, assuming they are stock 15s, if I were to go to pods, how much more of a pilot jet should I need? I am ordering some other parts and would like to pick up some jets at the same time.
 
MisterCinders said:
I, too, want to explore pods and jetting for my 78 GS750. I have air box (hate it) and VH 4-1 exhaust. Right now it is running lean but shows no air leaks. As I wrestle with the snipe hunt for this problem, I wonder if that is a pilot jet problem as well? In any event, I want to switch to pods and adjust the jetting.

My mains are 102.5. How do I check the pilot jet size? In any event, assuming they are stock 15s, if I were to go to pods, how much more of a pilot jet should I need? I am ordering some other parts and would like to pick up some jets at the same time.
Click to expand...

The pilot jets usually stay the same, there's not much difference in intake restriction at the low throttle openings where the pilots are in charge. And needed change can probably be done with the fuel and air screws. Pull the jet out, the number is on the side, should be a 15. The more airflow, the more change in restriction, so the needle (mid throttle) will want to come up a bit, and a much bigger main jet (full throttle). A pipe with stock airbox takes a smaller main jet change than going to pods. Pods and pipe, probably a 120 something main jet, just a wag.
 
Can someone give me jetting recommendations for a 77 GS 550 with straight through EMGO Dunstall style glasspack mufflers and EMGO pod air filters??? Here is the stock info that I have gathered from threads:


VM22SS GS550 1977 specs

ID 47110
idle RPM 1150
fuel level 4.0mm +/-1.0mm
float height 24.0mm +/-1.0mm
main jet #80 stock
main air jet 1.4mm stock
jet needle # 5DL35-3
needle jet # O-6
pilot jet #15
pilot air jet N/A
second pilot jet #50
throttle valve cutaway 1.5
throttle valve ????
bypass 1.0mm
pilot jet outlet 0.6mm
valve seat???
starter jet #????
pilot screw 1 (turn out???)
pilot air jet #??????
cable play ????mm
mixture screw setting 2 turns out
 
I dug up a Vance and Hines instruction sheet for their Suzuki 4 into 1 exhaust, and it recommended upgrading to pods at hte same time I believe, and said that for a GS550 (stock #80 mains) to upsize to a #97. I was unsure of what year the recommendation was good for, as I am not sure if this would hold true for 77-79 VM22SS carbs the same as it would for 80+ CV(?) style carbs. Judging from your 750 recommendations proportioned to a 550, it sounds like a move from 80 to 97 is just about right on the mains, and if I put K&N's on it, maybe the guy saying 125 was best would be telling me to go to a 100 or 102.5 mains?
 
rrok220 said:
I dug up a Vance and Hines instruction sheet for their Suzuki 4 into 1 exhaust, and it recommended upgrading to pods at hte same time I believe, and said that for a GS550 (stock #80 mains) to upsize to a #97. I was unsure of what year the recommendation was good for, as I am not sure if this would hold true for 77-79 VM22SS carbs the same as it would for 80+ CV(?) style carbs. Judging from your 750 recommendations proportioned to a 550, it sounds like a move from 80 to 97 is just about right on the mains, and if I put K&N's on it, maybe the guy saying 125 was best would be telling me to go to a 100 or 102.5 mains?
Click to expand...

i would have to say 100 would be spot on for you with pods and a 4-1 pipe it will definitely run and everything but you should do a plug chop in the really high RPM's range..
 
I was just referring to the V&H 4into1 instructions as a suggestion for aftermarket exhaust. Although I am well aware of the scavenging effect benefits of an X pipe on cars' dual exhaust and a 4into1's on bikes, we opted for some fairly inexpensive straight through glasspack "Dunstall" style mufflers, which you can see straight through but are looking through a single perforated baffle. I would imagine that they are fairly free flowing! perforated inner tube wrapped partially in fiberglass, and this single flow-through perforated baffle that forces some exhaust through the perforated inner tube and into the outer chamber.

I will look into some 100's, however, as we have also upgraded to Dyna electronic ignition instead of the points, as well as bigger gaps, bigger wires, and upgraded coils. Tell me if 102.5 is more in order in your opinion.
 
rrok220 said:
I was just referring to the V&H 4into1 instructions as a suggestion for aftermarket exhaust. Although I am well aware of the scavenging effect benefits of an X pipe on cars' dual exhaust and a 4into1's on bikes, we opted for some fairly inexpensive straight through glasspack "Dunstall" style mufflers, which you can see straight through but are looking through a single perforated baffle. I would imagine that they are fairly free flowing! perforated inner tube wrapped partially in fiberglass, and this single flow-through perforated baffle that forces some exhaust through the perforated inner tube and into the outer chamber.

I will look into some 100's, however, as we have also upgraded to Dyna electronic ignition instead of the points, as well as bigger gaps, bigger wires, and upgraded coils. Tell me if 102.5 is more in order in your opinion.
Click to expand...

honestly i think the bike will fine with 102.5's especially if it makes you feel better:D i know 125's made me lol...some of the guys on here told me while i was trying to trouble shoot my problem that they ran like 135's temporarily because he had nothing else and the bike ran so they told me too look elsewhere, and they were right it had to do with my points... i dont think it will have THAT MAJOR of an impact but 102.5's sound good to me i would get them if i were you and im pretty darn sure the bike will run good and also you cant go wrong with 100's
 
Thanks! Now if I could just find two replacement o-6 needle jets somewhere... not sure how they got cracked, but they are. VM22 o-6 jets seem out of production according to Sudco. starting a new thread on this problem.
 
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